Vehicle brake



J l 11, 1939. E; EN'GEL 2,165,358

I V I VEHICLE BRAKE Filed June 14. 1935 2 Sheet s-Sheet 1 fly. 1.

E. ENGEL VEHICLE BRAKE Filed June 14/ 1935 Fly. 3

July 11", 1939.

v 2 Sheets-Sheet 2 Patented July 11, 1939' Q VEHICLE BRAKE Ernst Engel, Frankfort-on-the-Main, Germany, assignor to Alfred Teves Maschinenund Armaturen-Fabrik Gesellschaft mit beschrankter Haftung, Frankfort-on-the-Main, Germany Application June 14, 1935, Serial No. 26,676

In Germany February 11, 1935 4 Claims. (Cl. 188-106) In vehicles such as motor vehicles, tram-cars mechanism for connecting two braking systems and the like, two brake operating gears are usuto operate one in the event of the failure of the ally provided which can be operated independother.

ently of one another. One is usually constructed Fig. 6 is a horizontal sectoinal view of a detail 5 as a foot actuated mechanism and is employed. on the line VI-VI of Fig. 5. 5 for normal braking purposes whereas the other In the embodiment according to Fig. 1, the

is usually constructed as a hand actuated gear cylinder in which the hydraulic pressure isproand is generally only employed if for any reason duced is indicated by numeral I. In it operates the foot operated gear fails. a piston 2 which by means of the link 3, the It can, however, occur that on abrupt bra-king lever 5 pivoted at l, and the rod 6 is connected 10 in an emergency the first or foot operated gear to the foot-actuated lever 8 pivoted at 'I. The will fail and the driver will need to be in a posipressure cylinder l is connected on the one hand tion to immediately grasp the hand lever and. with the reservoir 9 for the braking fluid and on apply the second or hand operated gear. The the other hand by way of the conduit II with object of the present invention is to provide for the two hydraulic brake cylinders II and I2 15 automatic actuation of a second brake operating which are provided on the wheels or pairs of gear po d ng to the usual hand operated wheels l3 and ll of the vehicle in known manner. gear by the foot-operated lever if the first brake The second brake gear is actuated from the operating gear fails, and according to the inhand lever I5 which is pivoted at l6 and through vention the two brake operating gears are autothe intermediary of the link ll engages the 20 m t a y c up together for D e, in lever 18 which operates on a cam is provided the case of a foot actuated hydraulic operating in the brake arrangement of the wheel I: which, gear, the force transmitting liquid has leaked again in known manner, operates the two brake out, or ii in the case of a compressed air brake jaws 20 and 2|. By means of the rod 2 th s operating system, the compressed air is not under mechanical brake arrangement is connected with the requisite pressure or the conduit therefor that of the wheel or wheels I. has been damaged. Both brakes, the hydraulically operated brake .T e coupling of h tw brake p r g gears and the mechanically operated brake, can be or'system is effected by the provision of a sepaoperated independently of each other. The two te Cy eq pp with a piston which is actuating levers 8 and ii of the two brake op- 30 connected with the pressure conduit for the force erating gears can however be connected by the transmitting liquid f a y r uli g ar or f r he rod 23 which at its end carries a slide 24 in which Compressed Of an Operated g a h p sa block 25 is slidable, the block 25 being pivotally t o s y der is subjected to the action of attached to the end ofv the foot-actuated lever I. a pi s and this sp s o pressed by the The slide 24, normally, may be movably sup- 35 pressure of the fluid force transmitting medium. o ted by engagement of pin 25a in arcuate slots If the pressure of the force transmission fluid 24 th th lide 24 is a. forked member falls then the spring displaces the pisto and 26 carried on the small piston 28 disp'laceable in with it a couplmg member which connects the the cylinder 21. The cylinder 21 is pivotal about 40 foot-actuated lever with a hand-actuated lever 29 and is connected with the hydraulic pressure in such manner that a further actuation of the conduit m by a flexible pipe line The mode former occasions the actuation of the brake opof operation is as follows.

By m to ver 8 the piston 2 is displaced in the pressure by way of example in the accompanyl-ng drawcylinder l by means of the rod 6 and the levers 45 ings in which:

Fig. 1 diagrammatically shows an embodiment 5 a and thus the brakmg fluid in the in the case of an ordinary motor vehicle with duit I0 is sub ected to pressure so that the brake hydraulically actuated brakes, cylinders It and I! come into operation and the Fig. 2 is intended for a tram-car or like vebrake s are p As the block 25 is 50 hicle comprising two driving stations each proplaceable in the slide 24, the motion of the footvided with corresponding brake levers. actuated lever B does not re-act on the hand- Figs. 3 and 4 show two different settings of a actuated lever I5. The hand-actuated lever l5 third embodiment. can be moved independently, whereby the me- Fig. 5 is an enlarged side sectional view of chanical brake gear associated therewith is ap- 55 shown in Fig. 1.

If, however, the pressure in the conduit l drops, due perhaps to a leak, then the pressure operating on the piston 28 through the flexible conduit 30 is also reduced and the spring 3| displaces the piston 28 upwardly whereby the fork 26 embraces the block 25 and prevents it from moving relatively to the slide 24. In this. way the foot-actuated lever 8 is connected with the lever l5 by way of the rod 23, and the-foot-actuated lever 8 now operates on the lever l5 and thus on the second or mechanical brake operating means by way of. the levers l1, l8 and 22. Thus it is not necessary for the driver to grasp the hand lever when the hydraulic gear failsbut the mechanical gear is immediately connected with the foot-actuated lever by the coupling arrangement.

In the embodiment according to Fig. 2, the brake arrangement is shown for a tram-car or like vehicle in which the brakes are to be actuated from two driving stations alternatively. Here the modification is introduced that the foot-actuated lever B does not operate directly on the pressure piston of the hydraulic pressure device but on a pneumatic pressure relay device which in turn actuates the hydraulic piston A compressed air cylinder 32 is provided in which the piston 33 is displaceable. This piston is connected by means of the rod 34 with the lever 36 which is pivoted at 35 and is accommodated within the reservoir 9 for the braking fluid. The lever 36 'operates on the piston 2 of the hydraulic cylinder I. This is again followed by the conduit I I! which as in the first embodiment is connected with the brake cylinders H, l2 of the two wheels or sets of wheels l3 and M.

In front of the piston 33 the cylinder 32 is connected'with the compressed air container 38 by the conduit 31. A piston valve 39 serves to prothe piston valve 39 is so disposed that compressed air can pass from the reservoir 38 to the cylinder 32 in front of the piston 33 to displace the latter whereby the hydraulic piston 2 is displaced within the cylinder I and the brake is applied by the hydraulic gear.

If the pressure in the compressed air container 38 falls then the springs 3| urge the plungers 28 upwardly so that the forks 26 embrace the sliding blocks 25 and thus couple the foot-actuated levers 8 with the levers l5 so that thenthe motion of the foot-operated levers 8 actuates directly on the mechanical brake gear.

The coupling device can of course be of any other kind differing from that described and shown, it merely being important that at the moment of failure of one brake the coupling automatically connects the two brake gears together.

Instead of the hydraulic braking gear any other suitable braking gear such as a mechanical brake can be employed.

As the spring 31 operates on the piston 28 a certain preliminary pressure is applied in the brake conduit, which prevents the formation of hollow spaces in the liquid in the brake conduit when the brake liquid contracts.

In the arrangement shown in Fig. 2 provision is made for the foot-actuated lever to be coupled with the hand-actuated lever for the other brake if the compressed air conduit becomes leaky but provision is not made for this connection to be effected if the pressurein the fluid conduit fails, although, as mentioned above, this contingency can be guarded against by providing a separate control for the coupling device responsive to the pressure in the braking fluid conduit. Constructions will now be described with reference to Figs. 3 and 4 in which the desired automatic coupling is obtained in this case also without the use of a separate control mechanism for the coupling de vice. In these constructions a discharge aperture is provided at a suitable point in the compressed air cylinder through which the air can escape from the cylinder if in consequence of a. reduction in pressure in the fiud conduit the piston is urged too far forwardly. After the piston has passed over this aperture, the air can escape through it and in this way it is attained that the d or r pt his c nnec n n on coupling device between pedal and hand lever is other side the aperture 49 enables the pressure in front of the piston 33 to be relieved.

The piston valve 39 is connected with one of the foot-actuated levers B by way of the lever M and the rod 42 and simultaneously it is connected with the foot-actuated lever B at the other driving station by way of the lever 43 and the rod 44. At both driving stations the hand actuated levers for the mechanicalbrake gears are again indicated by I5. They are pivotal about l6 and are connected with the mechanical part of the brake gears by means of a suitable linkage 45, 46. Ateach driving station the foot-actuated lever 8 can be connected with the hand lever I5 by means of a rod 23 which carries a slide 24 in which the block 25 carried at the end of the associated foot actuated lever I is displaceable. Disposed beneath each slide 24 is a coupling fork 26 with associated pistons 29, springs 3| and cylinders 21 which are pivotal about pivots 29. By means of the flexible conduits 41 and 48 the spaces in the two cylinders 21 above the pistons 28 are connected with the conduit 31 leading to the compressed air container 38.

If onenfthefoot-actuatedlevers 8 is actuated, then by way of the linkage 42, H. or 44, 43, 4|,

brought into operation.

The reference numerals employed are thesame as those in Fig. 2 and only the compressed air and pressure cylinders with the controlling piston valve 39 are shown in Figs. 3 and 4. In other respects the arrangement is as in Fig. 2. Within the cylinder 32 is the piston 33 which is connected by means of the rod 34 with the lever 36 pivoted at 35 and carrying the pressure piston 2 within the pressure cylinder I. Provided in the wall of the cylinder 32 is an aperture 48 which normally lies behind the piston 33 even in the extreme braking position as shown in Fig. 3.

If, perhaps due to a leak, the pressure falls in the pressure conduit in leading to the brake cylinders at the wheels, then under the action of the compressed air working on the piston 33, this piston and also the small piston 2 are displaced further to the right when the brakes are applied...

The piston thus assumes the position shown in Fig. 4 in which the piston 43 has passed beyond the opening 48 and exposes the same so that now all the compressed air can escape from the reservoir and from the compressed air conduit and thus the coupling device between foot-actuated aieasss and hand-actuated levers of the two brakes becomes operative.

I claim:

1. A vehicle brake system comprising a set of brakes, a'hydraulic brake operating gear, a separate brake operating gear, a slotted guide associated with the said'separate operating gear, a member associated with the hydraulic operating gear slidabie in said guide, a forked device to embrace said slidable member to hold it against motion relatively to said slotted guide, a plungerconnected to said forked device, a cylinder within which said plunger operates, a spring ur in said plunger to bring said forked device into engagement with said slidable member and a conduit connecting the conduit for the hydraulic medium with said cylinder on the side of the plunger oppomte to the spring. v

2. A vehicle brake system comprising a set of 2o brakes, a hydraulic brake operating gear, an independently operable brake-operating gear, a compressed air reservoir, a cylinder, a'conduit connecting said reservoir with said cylinder,'a-

piston movable in said cylinder under the action 5 of the compressed air to operate the hydraulic brakes, valve mechanism in said conduit for controlling the e of compressed air to said cylinder, means for operating said valve mechanism and means responsive to the failure of pres- -30.sure in said conduit between the reservoir and the valvemechanism for coupling said valve mechanism operating means with said independently operable brake operating gear.

3. A vehicle brake system according to claim 2,

' and means responsive to the failure of pressure of the fluid medium for coupling the valve mechanism operating means with the independently operable brake operating gear.

4. A vehicle brake system comprising, a set brakes, a hydraulic brake operating gear, an independently operablebrake operating gear, separable manual actuating devices for each of said gears, the hydraulic brake operating gear having a pneumatic relay controlled by the actuating device of the hydraulic gear, said relay having a cylinder, a piston slidable therein, mechanical piston to the fluid of the hydraulic gear, a compressed air supply, a conduit from said supply to said one end of said cylinder to cause the piston valve means controlled by the manual actuating means of the hydraulic brake operating gear for controlling the admission of air to said cylinder, the cylinder having an opening in its wall, be-

yond the normal position of the piston when the brakes are applied thereby, for enabling free escape of compressed air from said cylinder when th piston passes said normal position, and means responsive to the failure of pressure of the relay actuating air for coupling the manual actuating device of the hydraulic gear with the independently operable gear upon reduction of the pres-- pressure.

.means for applying operating pressurefrom said to move in the cylinder when air is admitted,

sure of the relay actuating air below a certain ERNST ENGEL. 

